<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8" />
		<meta name="viewport" content="width=device-width, initial-scale=1">
		<title>web site</title>
	</head>
	<body>
		<script>
// 			var num = 10;
// 			fun();
// 			function fun(){
// 				console.log(num);
// 				var num = 20;
// 			}
// 			
// 			var a = 18;
// 			f1();
// 			function f1(){
// 				var b=9;
// 				console.log(a);
// 				console.log(b);
// 				var a = '123';
// 			}
// 			
			
			console.log(cc);
			console.log(bb);
			console.log(aa);
			f2();
			function f2(){
				var aa = bb = cc = 9;
				console.log(aa);
				console.log(bb);
				console.log(cc);
			}
		</script>
	</body>
</html>